Post date: Apr 10, 2012 6:55:15 PM
Scientists in the Bahamas are exploring subterranean waterways accessible only through "blue holes" at the surface in search of clues to the islands' development over thousands of years. The researchers have found perfectly preserved fossils in the caverns, but say they have only scratched the surface. Katharine Jackson joined them.
REUTERS/ UNDERWATER VIDEO BY CO-PRODUCER RAMON LLANEZA - DIVER BRIAN KAKUK, BAHAMAS CAVE RESEARCH FOUNDATION SAYING:
"OK. Going in."
Going in to a blue hole in The Bahamas, diver Brian Kakuk enters an underwater world where remnants of the past are preserved in the present.
More than 120 feet down, Kakuk collects plant and animal fossils thousands of years old that are still intact in the blue hole's oxygen-poor environment.
BRIAN KAKUK, BAHAMAS CAVE RESEARCH FOUNDATION SAYING:
"Blue holes are literally time capsules and they hold this history that we didn't even know existed here. We're finding animals that we didn't know lived here and those animals are indicators of environments that we didn't know existed."
A blue hole is a circular sinkhole formed when the island's limestone surface eroded during the last ice age. As sea level rose, the deep holes filled with water, making them appear a deeper blue than surrounding shallow water.
A top layer of rainwater inhibits oxygen in most blue holes, thereby preserving things that fall into the hole and die.
A National Science Foundation-funded team is studying blue holes on the island of Eleuthera to create a timeline of its history.
Looking at a meter-long column of sediment, pollen expert Pat Fall says the blue hole might once have been dry, about 11,000 years ago.
PAT FALL, SCIENTIST, ARIZONA STATE UNIVERSITY SAYING:
"The red-brown might be an area that was at the bottom of the cave when it was exposed to the air. That would be my best guess….That's what we're hoping for, a record before humans...ON CAM Humans come to The Bahamas about a thousand years ago and then we'll have that change to the modern environment."
DAVID STEADMAN, ORNITHOLOGIST, UNIVERSITY OF FLORIDA SAYING:
"This is a bone of a hutia, the extinct rodent. This is a femur."
Ornithologist David Steadman is looking for animal bones, with help from his class of University of Florida students. He says the blue hole's inverted cone structure makes it hard to escape.
DAVID STEADMAN, ORNITHOLOGIST, UNIVERSITY OF FLORIDA SAYING:
"The sinkhole itself acts as sort of a natural trap. You can imagine a tortoise or a crocodile wandering around, falling in, in what ends up being a one way trip to a blue hole."
Blue holes also hold human bones. Nancy Albury - a curator at the National Museum of the Bahamas - says ancient Lucayan people believed blue holes were sacred.
NANCY ALBURY, NATIONAL MUSEUM OF THE BAHAMAS CURATOR OF PALEONTOLOGY, SAYING:
"Lucayans would come and they buried their dead in the blue hole because they believed it was a portal into the next world."
But for all the light blue holes shed on a distant past, their harsh conditions keep them shrouded in darkness.
Low oxygen allows dangerous gasses to build and tight passageways make many caves impenetrable. Only the most tolerant organisms can survive in them. Some microorganisms are thought to exist nowhere else in the world.
Because of its danger, human exploration has been limited.
BRIAN KAKUK, BAHAMAS CAVE RESEARCH FOUNDATION SAYING
"All the highest peaks have been climbed. All the jungles have been searched and explored. And here it is 2012, and you're still an explorer, you still have the opportunity to be an explorer. Every week, I go into places where no other humans have ever been before and that's really a unique opportunity and then to find things that no one has ever seen before as well."
There are more than one thousand blue holes in The Bahamas. All of them are believed to connect to the ocean through a network caves and tunnels. The National Museum of the Bahamas says only about 10 percent of the islands' blue holes have been explored.
...blue holes that hold secrets of life - past and present - secrets they may keep forever.
Katharine Jackson, Reuters.